A pipe connecter called a quick connector is used prevalently for, for example, connecting fuel pipes of automotive fuel supply systems.
A quick connector includes, as principal components, a male connector to be connected to a pipe, a female connector to be connected to a pipe, and a retainer for holding the male and the female connector together. The quick connector is able to connect the pipes without using any fasteners, such as bolts, simply by inserting the male connector in the female connector.
The type quick connecters of various structural designs have been devised. The quick connector is required to have a function to achieve firm connection, a function to facilitate disconnection, a function to achieve high-sealed connection, and a function to avoid incomplete connection. Incomplete connection is false connection in which the male and the female connector are held together with a retainer with the male connector incompletely inserted in the female connector. An improved quick connector constructed to prevent incomplete connection is disclosed in, for example, U.S. Pat. No. 5,542,716 (JP-A No. 50923/1998).
FIGS. 9 to 11 show a conventional quick connector.
FIG. 9 shows a female connector 12 and a male connector 14 of a quick connector 10, FIG. 10 shows a retainer 16, and FIG. 11 shows the female connector 12 and the male connector 14 completely connected together by the retainer 16 in a longitudinal sectional view.
Basically, the quick connector 10 is designed so that the retainer 16 is unable to achieve a locking function when the same is inserted through an opening 19 in the female connector 14 unless the male connector 14 is completely inserted in the female connector 12 to prevent incomplete connection.
Referring to FIGS. 9 and 11, the female connector 12 has a connecting part 13 to be pressed in a pipe, not shown, and a cylindrical housing 15 formed integrally with the connecting part 13. The female connector 12 is provided internally with a stepped, axial bore 17. The housing 15 has a connecting part 18 in which the male connector 14 is inserted. The connecting part 18 is provided with an opening 19 through which the retainer is inserted in the connecting part 18. An opening 19a similar to the opening 19 is formed opposite to the opening 19 in the connecting part 18. The housing 15 has the connecting part 18, a first cylindrical part 21a extending from the connecting part 18 and having a diameter smaller than that of the connecting part 18, and a second cylindrical part 21b extending from the first cylindrical part 21a and having a diameter smaller than that of the first cylindrical part 21a. 
The male connector 14 is provided on its outer circumference with an annular ridge 20 at a predetermined distance from one end thereof. The annular ridge 20 engages in a groove formed in the retainer 16 when the retainer 16 is inserted in the connecting part 18 to restrain the male connector 14 from axial movement.
As shown in FIG. 10, the retainer 16 is a substantially U-shaped plastic member formed by molding. The retainer 16 has a body 22 having opposite, parallel side walls 23a and 23b. Retaining lugs 24a and 24b respectively having curved inner surfaces are formed on the inner surfaces of the side walls 23a and 23b, respectively. The retaining lugs 24a and 24b are capable of coming into close contact with the outer circumference of the male connector 14.
Referring to FIG. 11, the opening 19 of the female connector 12 has an axial length L, and the retainer 16 has a length approximately equal to the length L of the opening 19. The opening 19 has a width, i.e., a dimension along a direction perpendicular to the axis of the female connector 12, substantially equal to the width of the retainer 16, i.e., a dimension along a direction perpendicular to the axis of retainer 16. Opposite axial ends of the opening 19 are defined by a front end wall 25a and a rear end wall 25b. The width L1 of a gap between the front end wall 25a, and the front end surfaces 26a of the retaining lugs 24a and 24b of the retainer 16 is substantially equal to slightly greater than the width of the annular ridge 20 of the male connector 14. The positional relation between the annular ridge 20 of the male connector 14, and a space 34 between the front end surfaces 26a of the retaining lugs 24a and 24b of the retainer 16 is determined as to meet the following condition. In a state where the male connector 14 is inserted completely in the female connector 12 such that the front end of the male connector 14 is pressed against a step between the connecting part 13 and the second cylindrical part 21b or the annular ridge 20 is in contact with a top hat 32 serving as a pressing member, the annular ridge 20 is located in the space 34. When the annular ridge 20 is thus located in the space 34, the retainer 16 can be pressed through the opening 19 in the connecting part 18 of the housing 15.
When the retainer 16 is held opposite to the opening 19, the male connector 14 is inserted in the female connector 12 so that the annular ridge 20 is placed in the space 34, and then the retainer 16 is pushed through the opening 19 into the connecting part 18 of the female connector 12, retaining ridges 30a and 30b formed along the lower edges of the side walls 23a and 23b on the outer side surfaces of the side walls 23a and 23b, respectively, engage the lower edges of side walls extending between the end walls 25a and 25b, respectively, to retain the retainer 16 in the connecting part 18 of the female connector 12.
When the retainer 16 is set normally in place on the female connector 12, the front end surfaces 26a of the retaining lugs 24a and 24b of the retainer 16 are in contact with the annular ridge 20 of the male connector 14 to restrain the male connector 14 from backward axial movement. Thus, the female connector 12 and the male connector 14 are firmly inseparably connected together.
A gap between the outer circumference of the male connector 14 and the inner circumference of the first cylindrical part 21a is sealed by O rings 31a and 31b. A spacer 33 is interposed between the O rings 31a and 31b, and the O rings 31a and 31b are held in the gap between the outer circumference of the male connector 14 and the inner circumference of the first cylindrical part 21a and by the top hat 32. Thus, the O rings 31a and 31b are unable to come off the gap into the connecting part 18.
The incomplete connection preventing mechanism of the pipe connector shown in FIGS. 9 to 11 enables the retainer 16 to be inserted through the opening 19 into the connecting part 18 only when the annular ridge 20 is placed in the space 34 to prevent to prevent the false connection of the female connector 12 and the male connector 14 due to the incomplete insertion of the retainer 16 in the connecting part 18.
However, the following problem arises because practical pipe connectors of this type respectively having different sizes need female connectors and male connectors respectively having different sizes.
For example, male connectors 14 of different sizes differ from each other in the length between the annular ridge 20 and the front end. If the retainer 16 is inserted in the connecting part 18 before inserting the male connector 14 in the female connector 12, the annular ridge 20 comes into contact with the rear ends 26b of the retaining lugs 24a and 24b of the retainer 16 as shown in FIG. 12 and, consequently, the male connector 14 cannot be properly inserted in the female connector 12, and the female connector 12 and the male connector 14 are connected incompletely. If a front part extending forward from the annular ridge 20 of the male connector 14 has a long length, the front part of the male connector 14 will reach the O ring 31b and the O ring 31b will become effective. Consequently, it is possible that the incompletely connected pipe connector passes a pressure test and incomplete connection is overlooked. To avoid such incomplete connection, the length of the retainer 16 must be increased so that the rear end surfaces 26b of the retaining lugs 24a and 24b are shifted toward the rear end of the female socket 12 to prevent the front part extending forward from the annular ridge 20 of the male connector 14 from reaching the O ring 31b, which increases the respective lengths of the housing 15 and the retainer 16.
To avoid increasing the length of the housing 15 of the female connector 12 to be connected with a male connector having a long front part extending forward from an annular ridge 20, the position of the annular ridge 20 in a state where the male connector and the female connector 12 are connected normally must be shifted backward with respect to a direction in which the male connector is inserted in the female connector 12 to shift the front end surfaces 26a of the retaining lugs 24a and 24b backward. Therefore, in some cases, the distance L2 between the front end wall 25a of the female connector 12 and the front end surfaces 26a of the retaining lugs 24a and 24b becomes unavoidably considerably long as shown in FIG. 13. When the female connector 12 is formed in a structure as shown in FIG. 13, it is possible that the pressure tightness of the pipe connector is reduced and, when the pressure in pipes connected to the pipe connector becomes high, that the top hat 32 is forced into the connecting part 18, the O rings 31a and 31b are dislocated and the sealing effect thereof is nullified, even if the retainer 16 is engaged normally with the female connector 12 to connect the female connector 12 and the male connector completely.
The following problem arises even in a state shown in FIG. 11, where the retainer 16 functions normally and the female connector 12 and the male connector 14 are completely connected together. When piping is arranged such that the pipe connector 10 shown in FIG. 11 is set upside down, it is possible that water formed by condensation or the like collects in the space 34 between the front end wall 25a, and the front end surfaces 27a of the retaining lugs 24a and 24b, and the female connector 12 will be corroded if the female connector 12 is formed of a metal.
The foregoing problems in the prior art are attributable mostly to false connection of the female connector 12 and the male connector 14 incompletely inserted in the female connector by the retainer 16. Another problem in the prior art is the false assembly of the female connector 12 and the retainer 16.
When shipping a conventional quick connector, the female connector 12 and the retainer 16 are wrongly combined by false assembly.
Some conventional quick connector 10′ includes a directional retainer 16 which must be set in a specific position in a female connector 12 as shown in FIG. 14. In the conventional connector 10′ shown in FIG. 14, the rear end surfaces 26b of retaining lugs 24a and 24b not in contact with an annular ridge 20 formed on a male connector 14 are formed so as to be in contact flat with a rear end wall 25b. Therefore, the retainer 16 must be inserted through an opening in the female connector 12 with the front end surfaces 26a, which engages the annular ridge 20, of the retaining lugs 24a and 24b facing the front.
As shown in FIG. 15(a), the side walls of the connecting part 18 of a female connector 12 are provided in their horizontal upper edges with recesses 37, and the side walls 23a and 23b of a retainer 16 are provided with projections 38 which engage in the recesses 37, on their outer surfaces, respectively. The projections 38 are formed at positions somewhat behind the middle points of the side walls 23a and 23b, respectively, to make a distinction between the front and the rear end of the retainer 16 in appearance, and the positions of the recesses 37 are determined so as to correspond to those of the projections 38.
FIG. 15(a) shows the female connector 12 and the retainer 16 in a correct assembly. When the quick connector 10′ is shipped from a factory, the retainer 16 half-inserted in the female connector 12 such that an upper half part of the retainer 16 protrudes from the connecting part 18 to prevent false connection.
However, it often occurs that the retainer 16 is inserted wrongly in the connecting part 18 in a reverse position as shown in FIG. 15(b). However, the difference between a correct assembly of the female connector 12 and the retainer 16 and a wrong assembly of the same is not so significant as to enable making a clear distinction between the correct and the wrong assembly at a glance and, consequently, wrong assemblies are overlooked and are delivered to customers.
If the retainer 16 is reversed, the retainer 16 is unable to lock together the female connector 12 and a male connector 14 inserted in the female connector 12 by pushing the retainer 16 into the female connector 12 because the projections 38 rest on the horizontal upper edges 16a of the side walls of the connecting part 18, so that false connection can be avoided. In such a case, the user needs additional work for pulling out the retainer 16 from the female connector 12 and inserting the retainer 16 in a correct position in the female connector 12.
Moreover, it is possible that the retainer 16 is inserted through the other opening 19a on the side of lower horizontal edges 16b of the side walls not provided with any recess in the female connector 12 as indicated by two-dot chain lines in FIG. 15(b).